pre ap chem UNIT 2 review

law of conservation of mass

Matter is not created nor destroyed in any chemical or physical change

law of definite proportions

a given compound always contains exactly the same proportion of elements by mass

law of multiple proportions

elements can combine in different ratios to form different compounds

atom

smallest particle of an element that demonstrates properties of that element

atomic number

the number of protons in the nucleus of an atom that determines the identity of the element

isotopes

Atoms of the same element that have different numbers of neutrons from each other (mass number)

radioactivity

when unstable atoms give off energy of particles to become stable

nuclear fusion

a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.

nuclear fission

a nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy

nuclear equation

a type of equation that shows the atomic number and mass number of the particles involved

half-life

length of time required for half of the radioactive atoms in a sample to decay

aristotle

suggested matter was continuous

daltons atomic theory, atoms

of each element are identical in size, mass and other properties

What was the behavior of cathode rays in early experiments when exposed to a magnetic field?

Cathode rays were unaffected by a magnetic field.

What charge did cathode rays carry according to early experiments?

Cathode rays were found to carry a positive charge.

What was the significance of the deflection of cathode rays in Thomson's experiments?

The deflection was evidence of the particle nature of electrons.

In Rutherford's experiments, what happened to most positively charged particles as they passed through metal?

Most positively charged particles passed straight through the metal.

What was observed about the deflection of positively charged particles in Rutherford's experiments?

Very few were slightly deflected, while some were greatly deflected back from the metal.